Electromotor and pump unit

ABSTRACT

An electromotor and hydraulic pump unit with a sealed housing has a common drive shaft projecting with one end into a balancing pressure chamber in the pump stator. Pressure fluid flows along the shaft into a cavity of the housing in which the electromotor and the other shaft end are located so that the motor is cooled, the shaft bearings in the cavity lubricated by the pressure fluid, and the axial force acting on the bearings is reduced.

United States Patent Bertsch et a1.

Feb. 1, 11972 ELECTROMOTOR AND PUMP UNIT Inventors: Richard Bertsch,Asperg; Paul Fussner,

Sindelfingen; Manfred Glaser, Neckarweihingen; Hermann Nusser, Asperg,all of Germany Assignee: Robert Bosch Gmbl'l, Stuttgart, Germany Filed:May 21, 1970 Appl. N0.: 39,308

Foreign Application Priority Data May 28, 1969 Germany ..P 19 27 073.6

US. Cl ..4l7/4l0, 418/73 Int. Cl. ..F04h 17/00, F04b 35/04, F03c 3/00Field of Search ..417/371,410, 372, 369, 370;

[56] References Cited UNITED STATES PATENTS 2,681,010 6/1954 Hilken"415/104 2,809,590 10/1957 Brown ..4l7/370 X 3,267,868 8/1966 Page..417/370 Primary Examiner-Robert M. Walker AttorneyMichael S. Striker[57] ABSTRACT An electromotor and hydraulic pump unit with a sealed housing has a common drive shaft projecting with one end into a balancingpressure chamber in the pump stator. Pressure fluid flows along theshaft into a cavity of the housing in which the electromotor and theother shaft end are located so that the motor is cooled, the shaftbearings in the cavity lubricated by the pressure fluid, and the axialforce acting on the bearings is reduced.

9 Claims, 2 Drawing Figures PATENTED'FEB H872 Fig.7

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IN V EN TOR. Richard BER T56 H Paul F USS/YER BY Manfred GLASEI? IHermann Ill/555R ELECTROMOTOR AND PUMP UNIT BACKGROUND OF THE INVENTIONThe present invention relates to electromotor and pump units in whichthe pump and electromotor are mounted in a sealed housing which issubstantially filled with a pressure fluid under pressure, and in whichthe rotor of the electromotor runs in the pressure fluid so that thebearings of the motor shaft are lubricated by the pressure fluid. Motorsof this type are particularly used for fuel pumps, and a pump of thistype is disclosed in the US. Pat. No. 1,493,612.

The apparatus of the prior art has the disadvantage that impurities,such as particles of the collector brushes, enter the fluid which hasthe disadvantage that impurities and dirt may enter the carburetor towhich the fluid is pumped. Particles also float in the cavity of thehousing in which the electromotor is located, where they may causeincreased friction in the bearings, or even damage to the same,resulting in stopping of the pump. Another disadvantage of the prior artis that the motor shaft, which also carries the pump rotor, is subjectedto one sided axial pressure corresponding to the pressure produced bythe pump, so that the bearings are stressed in axial direction.

SUMMARY OF THE INVENTION It is one object of the invention to provide anelectromotor and pump unit in which the motor is cooled by the pressurefluid pumped by the pump, while the bearings of the shaft are lubricatedand cooled.

Another object of the invention is to reduce axial forces act ingthrough the shaft on the bearings so that the span of life of the unitis increased.

Another object of the invention is to provide an electromotor and pumpunit in which fluid circulated in the cavity of the motor housing, isfreed of impurities before again pumped by the pump to a consumer, suchas a carburetor.

With these objects in view, the common drive shaft of the motor andpump, has one end located in a balancing pressure chamber communicatingwith the pressure space of the pump, while the cavity in which the motorand the other shaft end are located communicate also with the pressurespace of the pump.

This arrangement results in a hydrostatic relief of the common pump andmotor shaft, so that the axial stress of the bearings of the shaft arereduced to a minimum. Furthermore, a part of the pressure fluid iscirculated through the cavity of the motor housing to effect cooling andlubricating of the electromotor and its bearing due to hydrodynamiceffects. This part of the pressure fluid passes through a filter beforeagain joining the main part of the pump fluid, so that dirt particlesand other impurities are filtered out of the pressure fluid which isdelivered by the pump to a consumer. Since only part of the pressurefluid circulates through the motor casing, in which it encounters greatflow resistance, the total energy losses are low.

An embodiment of the invention comprises an electromotor and-a pumpincluding motor and pump rotors, a common drive shaft supporting therotors, and motor and pump stator means surrounding the rotors,respectively, the pump stator means forming a pressure space having apressure fluid outlet and a suction space having an inlet, and alsoforming a balancing chamber communicating with the pressure space; andsealed housing means supporting the motor and pump stator means, andincluding a motor housing having a cavity, and bearing means in thecavity for supporting the common drive shaft in a position in which oneend of the same is located in the balancing chamber while the other endof the same is located in the cavity of the motor housing.

The balancing chamber communicates with the cavity, preferably through abore in the stator housing through which the shaft passes, so that thecavity is filled with the pressure fluid pumped by the pump. As aresult, the motor is cooled, the drive shaft is axially balanced, andthe bearing means are lubricated by the pressure fluid.

In a preferredembodiment of the invention, the balancing chamber isconnected with a pressure space of the pump by a radial channel, and thecavity in the motor housing is connected by a ,duct with the centralopening in the pump stator in which the pump rotor forms a workingspace. This duct is covered by flltermeans sothat pressure fluid flowingalong the shaft into the cavity and filling the same, can flow out ofthe cavity through the filter means and duct back to the working chamberof the pump.

In the preferred embodiment of the invention, a biassed valve slideconnects at the beginning of the operation the pressure space of thepump with the return outlet through a throttling means, and connects,when the pressure increases, the pressure space of the pump with apressure fluid outlet.

The, novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional ob jects and advantages thereof,will be best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is an axial sectional viewillustrating an embodiment of the invention; and

FIG. 2 is a fragmentary cross-sectional view taken II-II in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT A pot-shaped motor housing 4forms an inner cavity in which an electromotor 3 having a magnet. stator5 and a drive shaft 6 is located. The motor rotor is fixedly secured todrive shaft 6 which is mounted in bearings 7 and 8. The left end ofshaft 6, as viewed in the drawing, carries a pump rotor 29 and has afree end located in a balancing chamber 28. Bearing 7 is disposed in adished portion of the pot-shaped housing 4 which is made of steel. Theinner surface of the dished portion 9 has several grooves 10 located inaxial planes through which fluid can flow from the cavity 1 to a spacebehind the end of shaft 6 on the right side as viewed in the drawing. Adisk 11 is secured to the inner surface of housing 4 to hold bearing 7in place.

The pump stator includes a connector part 15, a stator plate 16, and asupport part 17 which are pressed together by bolts 18, see FIG. 2. Theend of support part 17 has a cylinder portion secured to the open end ofmotor housing 4 which is sealed by an annular sealing ring 13. Lugs 14are bent out of the cylinder wall of motor housing 4 to secure the sameto a flange of the cylinder portion 12 of support part 17 of the pumpstator means.

The support part 17 has a transverse wall l9 with a central bore 20through which shaft 6 projects into the balancing chamber 28in connectorpart 15. This end portion of shaft 6 carries the pump rotor 29 which islocated in an eccentric circular opening 22 in the stator plate 16, seealso FIG. 2. Bore 20 has a widened portion formed as a seat 20 forhearing 8 which is also held in place by plate secured to portion 24 ofsupport part 17 of the pump stator means.

Support part I7 and stator plate 16 abut each other with planarsurfaces, and are sealed by a sealing O-ring 24 located in a circulargroove 23 in surface 17 of support part 17, which is substantiallycircular and concentric with shaft 6.

Stator plate 16, and connector part 15, abut each other also with planarcircular faces. The surface 15' of connector part 15 has acirculargroove 25 in which a O-ring 26 islocated so that the working space inopening 22 formed by rotor 29 is completely sealed. The balancingpressure space 28 is concentric to shaft 6, and forms a circulardepression in surface 15'. Only a very short end portion of shaft '6 onthe left side of pump rotor 29 projects into balancing chamber 28.

The pump rotor 29 has a cylindrical rotary member formed with,substantially radial slots 30 with part-circular bottom portions, asbest seen in FIG. 2. Rollers 31 are respectively located in the slotsand roll during rotation of shaft 6 and member 29 on the wall of theeccentric circular opening 22. The revolving rollers 31 press fluid fromthe suction chamber 32 into the pressure chamber 33. The roller pistonpump 29, 31, 16 operates on the well-known principles of a radial pistonpump.

The suction space 32 is arcuate and follows the contour of the circularopening 22. The pressure space 33 has a corresponding shape and islocated on the other side of opening 22. Each arcuate space 33 and 32extends over an angle of substantially 110.

A channel 34 in the surface of connector part 15 extends in radialdirection with respect to the axis of shaft 6, and connects pressurespace 33 with the balancing pressure chamber 28. Consequently, the samepressure prevails in balancing chamber 28 as on the pressure side of thepump.

Connector part has a suction means 35 which may be connected with thefuel tank of an automobile, a pressure fluid outlet means 36, which maybe connected with the carburetor of a combustion engine, and a returnoutlet means, which may lead to the fuel tank.

The suction inlet 35' in the suction inlet means 35, communicates withthe arcuate suction space 32. The pressure fluid outlet 36 in outletmeans 34 communicates through a channel 38 with the pressure space 33.In this region of connector part 15, a blind bore 38 is providedperpendicularly to shaft 6 for guiding a valve slide 39 for slidingmovement in a sealed condition. At the bottom of the blind bore 38, anannular chamber communicating with pressure space 33 is provided.Channel 38' is coaxial with the blind valve bore 38, but has a muchsmaller diameter. The end of channel 38 at the bottom of the blind valvebore 38 is constructed as a seat for a portion 41 at the end of thepiston-shaped valve slide 39.

Valve slide 39 has on its outer cylindrical surface a narrow straightthrottling channel 42 which connects two annular throttling channels43,44 in the valve slide 39 with each other. The distance between theannular throttling channels 43 and 44 is selected so that the annularspaces formed by the same communicate on the one hand with the pressurespace 33, and on the other hand with the return outlet 37, when valveslide 39 is in the illustrated throttling position in which portion 41thereofcloses the channel 38.

Valve slide 39 is biassed by two springs 45 and 46 which have differentresilience. The softer spring 45 directly abuts slide valve 39 at oneend, and the spring plate 47 at the other end, which is urged by astronger spring 46 against a shoulder 48 in valve bore 38. The other endof spring 46 abuts a closure cap 49 which closes valve bore 38 and issecured to connector part 15 of the pump stator. A sealing ring 51 sealscap 49.

1n the region of the working chamber of the pump 29, 16, a duct 53,parallel to shaft 6, is provided in the wall portion 19 of supportingpart 17, penetrating the same. The end of duct 53 opening into thecavity 1 formed by motor housing 4 and supporting part 17, is covered bya filter means 54.

The electromotor 3 is connected by suitable insulated conductors to amultiple plug 55 which is mounted on an insulating body 56. A contactplate 57 is secured to the flange 12 of support plate 17, and carriesslide contacts, not shown. A sealing ring 58in the insulating body 56seals the cavity 1.

The roller piston pump 29,16 operates in a well-known manner whenelectromotor 3 is started. Pressure fluid is pumped from pressure space33 through channel 34 into the balancing chamber 28 from where thepressure fluid, for example fuel, flows along shaft 6 through bore intothe cavity 1. The volume may be 4 liter per hour. When at least themajor part of cavity 1 is filled with a pressure fluid, which alsoenters during this filling operation through the duct 53 and filter 54,a rinsing circulation is obtained. Cold fluid flows from the pumpthrough opening 20 along shaft 6 and bearing 8 so that heat produced byfriction is conveyed by the fluid. Due to the fact that the viscosity ofthe fluid is higher at a low temperature, the fluid entering bearing 8forms a good lubricating film in the same. In cavity 1 in the statorhousing 4, the fluid flows around the motor rotor which is also cooled,and then lubricates the bearing 7, flowing through grooves 10 behind theend faces of bearing 7 and shaft 6.

Due to the rotation of the rotor of electromotor 3, an outwardlydirected flow of fluid takes place in cavity 1, as has been found bytests, so that the now slightly warmed fluid flows through filter means54 and duct 53 back to the working space in stator plate 16. Sinceduring the operation of the pump, the greater part of the fluid pumpedby the same has flowed from pressure space 33 and channel 38' intopressure fluid outlet 36, as will be explained hereinafter, the fluidreturns from cavity 1 through duct 53 and combines in the working spaceof the pump with the other pumped fluid, which causes no harm to thecarburetor since the fluid has been cleaned by filter 54 before enteringthe working space of the pump.

At the beginning of the rotation of the pump by the motor 3, valve slide39 is in the position shown in FIG. 1. At the beginning of the pumpingoperation, at first only air or gases may be pumped which flow from thepressure space 33 through the annular throttling channel 43, andthrottling channel 42 to the annular throttling channel 44 whichcommunicates with the return outlet 37 so that the gases or the air arereturned to the fuel tank.

When the pump begins to pump liquid, for example gasoline, thethrottling effect of channels 40 and 42 is so great that the pressureincreases in chamber 40 and valve slide 39 is moved against the actionof spring 45 so that portion 41 of valve slide 39 opens channel 38 andthe pressure chamber 33 communicates with the pressure fluid outlet 36'.

At the same time, throttling channel 43 and throttling channel 42 areclosed.

When the pressure in the pressure chamber 33 further increases up to apermissible maximum, the valve slide 39 is moved against the force ofspring 46 so far in valve bore 38 that the pumped fuel can directly flowinto the return outlet 37 so that the pressure is relieved.

At the end of the pumping operation when electromotor 3 stops, valveslide 39 is returned to its initial illustrated position by the actionof the springs 45 and 46. Portion 41 of valve slide 39 closes againchannel 38 so that the connection between the pump and the tank of theautomobile is interrupted.

Instead of the roller piston pump, any other pump construction may beused, and the slide valve may be omitted or differently constructed.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofelectromotor and pump units differing from the types described above.

While the invention has been illustrated and described as embodied in anelectromotor and pump unit in which part of the pumped fluid iscirculated in a housing of the electromotor, it is not intended to belimited to the details shown, since various modifications and structuralchanges may be made without departing in any way from the spirit of thepresent invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

We claim:

1. Electromotor and pump unit comprising an electromotor and a pumpincluding motor and pump rotors, a common drive shaft supporting saidrotors, an motor and pump stator means surrounding said rotors,respectively, said pump stator means forming a pressure space having apressure fluid outlet and a suction space having an inlet, and alsoforming a balancing chamber communicating with said pressure space, saidpump stator means including a support part mounted on said housingmeans, a connector part having said inlet and outlet, and a stator platebetween said support part and said connector part and being formed witha central opening in which said pump rotor is located, said connectorpart having a surface in sealing contact with one side of said statorplate and being formed with said pressure space and said balancingchamber which communicate with said central opening for receivingpressure fluid, said support part being formed with a bore through whichsaid drive shaft projects into said balancing chamber with the end of anend portion carrying said pump rotor in said central opening; and sealedhousing means supporting said motor and pump stator means, and includinga motor housing forming with said pump stator means a cavity, andbearing means in said cavity for supporting said common drive shaft in aposition in which said end of the same is located in said balancingchamber while the other end of the same is located in said cavity ofsaid motor housing so that pressure fluid from said pressure space flowsthrough said balancing chamber and said bore along said drive shaft intosaid cavity so that said cavity is filled with the pressure fluid pumpedby said pump whereby said electromotor is cooled, said drive shaft isaxially balanced, and said bearing means are lubricated by said pressurefluid 2. A unit as claimed in claim 1 wherein said balancing chamber insaid connector part is concentric with said one end portion of saiddrive shaft; and wherein said connector part has a channel which extendsin radial direction between said balancing chamber and said pressurespace.

3, A unit as claimed in claim 1 wherein said support part is formed witha duct penetrating the same and having one end opening into said centralopening and another end opening into said cavity; and comprising filtermeans for filtering impurities out of fluid flowing through said duct sothat pressure fluid entering said cavity through said bore in saidsupport part along said drive shaft flows through said filter means andsaid duct out of said cavity.

4. A unit as claimed in claim 3 wherein said pump rotor includes arotary member secured to said drive shaft and formed with peripheralchambers, and rollers in said chambers; wherein said central opening hasa circular inner surface eccentric to the axis of said drive shaft andengaged by said rol lers so that working spaces are formed between saidpump rotor and said circular inner surface communicating with saidpressure and suction spaces in said connector part; wherein said ducthas said one open end communicating with said working spaces and theother open end thereof communicating with said cavity; and wherein saidfilter means are located in said cavity covering said other open end ofsaid duct.

5. Electromotor and pump unit comprising an electromotor and a pumpincluding motor and pump rotor, a common drive shaft supporting saidrotors, and motor and pump stator means surrounding said rotors,respectively, said pump stator means forming a pressure space having apressure fluid outlet and a suction space having an inlet, and alsoforming a balanc' ing chamber communicating with said pressure space,said pump stator means including a return outlet; valve meansspring-biassed to a throttling position connecting said pressure spacewith said return outlet, and being responsive to increased pressure insaid pressure space to move to an operative position connecting saidpressure space with said pressure fluid outlet; and sealed housing meanssupporting said motor and pump stator means, and including a motorhousing forming with said pump stator means a cavity, and bearing meansin said cavity for supporting said common drive shaft in a position inwhich one end of the same is located in said balancing chamber while theother end of the same is located in said cavity of said motor housing,said balancing chamber communicating with said cavity so that saidcavity is filled with the pressure fluid pumped by said pump wherebysaid electromotor is cooled, said drive shaft is axially balanced, andsaid bearing means are lubricatedby said pressure fluid.

6. A unit as claimed in claim 5 wherein said pump stator means is formedwith a valve bore; wherein said valve means include a valve slidemovable in said valve bore, and two springs having different resilienceabutting each other, one of said springs abutting said pump stator meansand the other spring abutting said one spring and said valve slidev 7. Aunit as claimed in claim 6 wherein the weaker spring is said otherspring, and the harder spring is said one spring; including a springplate between said springs; and a cap closing said valve bore, said oneharder spring abutting said cap and thereby said pump stator means.

8. A unit as claimed in claim 5 wherein said pump stator means is formedwith a channel connecting said pressure space with said pressure fluidoutlet; and wherein said valve means has a valve portion closing saidchannel in said throttling position and opening the same in saidoperative position; and wherein said valve means has throttling meansfor connecting said pressure space with said return outlet in saidthrottling position.

9. A unit as claimed in claim 8 wherein said pump stator means is formedwith a valve bore; wherein said valve means include a valve slide havingsaid valve portion and said throttling means, said throttling meansincluding a straight throttling channel extending in axial direction ofsaid valve slide and two annular throttling channels extending aroundsaid valve slide and connected by said straight throttling channel, oneof said annular throttling channels communicating with said returnoutlet, and the other annular throttling channel communicating in saidthrottling position with said pressure space.

1. Electromotor and pump unit comprising an electromotor and a pumpincluding motor and pump rotors, a common drive shaft supporting saidrotors, an motor and pump stator means surrounding said rotors,respectively, said pump stator means forming a pressure space having apressure fluid outlet and a suction space having an inlet, and alsoforming a balancing chamber communicating with said pressure space, saidpump stator means including a support part mounted on said housingmeans, a connector part having said inlet and outlet, and a stator platebetween said support part and said connector part and being formed witha central opening in which said pump rotor is located, said connectorpart having a surface in sealing contact with one side of said statorplate and being formed with said pressure space and said balancingchamber which communicate with said central opening for receivingpressure fluid, said support part being formed with a bore through whichsaid drive shaft projects into said balancing chamber with the end of anend portion carrying said pump rotor in said central opening; and sealedhousing means supporting said motor and pump stator means, and includinga motor housing forming with said pump stator means a cavity, andbearing means in said cavity for supporting said common drive shaft in aposition in which said end of the same is located in said balancingchamber while the other end of the same is located in said cavity ofsaid motor housing so that pressure fluid from said pressure space flowsthrough said balancing chamber and said bore along said drive shaft intosaid cavity so that said cavity is filled with the pressure fluid pumpedby said pump whereby said electromotor is cooled, said drive shaft isaxially balanced, and said bearing means are lubricated by said pressurefluid.
 2. A unit as claimed in claim 1 wherein said balancing chamber insaid connector part is concentric with said one end portion of saiddrive shaft; and wherein said connector part has a channel which extendsin radial direction between said balancing chamber and said pressurespace.
 3. A unit as claimed in claim 1 wherein said support part isformed with a duct penetrating the same and having one end opening intosaid central opening and another end opening into said cavity; andcomprising filter means for filtering impurities out of fluid flowingthrough said duct so that pressure fluid entering said cavity throughsaid bore in said support part along said drive shaft flows through saidfilter means and said duct out of said cavity.
 4. A unit as claimed inclaim 3 wherein said pump rotor includes a rotary member secured to saiddrive shaft and formed with peripheral chambers, and rollers in saidchambers; wherein said central opening has a circular innEr surfaceeccentric to the axis of said drive shaft and engaged by said rollers sothat working spaces are formed between said pump rotor and said circularinner surface communicating with said pressure and suction spaces insaid connector part; wherein said duct has said one open endcommunicating with said working spaces and the other open end thereofcommunicating with said cavity; and wherein said filter means arelocated in said cavity covering said other open end of said duct. 5.Electromotor and pump unit comprising an electromotor and a pumpincluding motor and pump rotor, a common drive shaft supporting saidrotors, and motor and pump stator means surrounding said rotors,respectively, said pump stator means forming a pressure space having apressure fluid outlet and a suction space having an inlet, and alsoforming a balancing chamber communicating with said pressure space, saidpump stator means including a return outlet; valve means spring-biassedto a throttling position connecting said pressure space with said returnoutlet, and being responsive to increased pressure in said pressurespace to move to an operative position connecting said pressure spacewith said pressure fluid outlet; and sealed housing means supportingsaid motor and pump stator means, and including a motor housing formingwith said pump stator means a cavity, and bearing means in said cavityfor supporting said common drive shaft in a position in which one end ofthe same is located in said balancing chamber while the other end of thesame is located in said cavity of said motor housing, said balancingchamber communicating with said cavity so that said cavity is filledwith the pressure fluid pumped by said pump whereby said electromotor iscooled, said drive shaft is axially balanced, and said bearing means arelubricated by said pressure fluid.
 6. A unit as claimed in claim 5wherein said pump stator means is formed with a valve bore; wherein saidvalve means include a valve slide movable in said valve bore, and twosprings having different resilience abutting each other, one of saidsprings abutting said pump stator means and the other spring abuttingsaid one spring and said valve slide.
 7. A unit as claimed in claim 6wherein the weaker spring is said other spring, and the harder spring issaid one spring; including a spring plate between said springs; and acap closing said valve bore, said one harder spring abutting said capand thereby said pump stator means.
 8. A unit as claimed in claim 5wherein said pump stator means is formed with a channel connecting saidpressure space with said pressure fluid outlet; and wherein said valvemeans has a valve portion closing said channel in said throttlingposition and opening the same in said operative position; and whereinsaid valve means has throttling means for connecting said pressure spacewith said return outlet in said throttling position.
 9. A unit asclaimed in claim 8 wherein said pump stator means is formed with a valvebore; wherein said valve means include a valve slide having said valveportion and said throttling means, said throttling means including astraight throttling channel extending in axial direction of said valveslide and two annular throttling channels extending around said valveslide and connected by said straight throttling channel, one of saidannular throttling channels communicating with said return outlet, andthe other annular throttling channel communicating in said throttlingposition with said pressure space.